1. Field of the Invention
The present general inventive concept relates to a liquid crystal display, and, more particularly, to a liquid crystal display wherein a printed circuit board equipped with light emission diodes serving as a light source is disposed on the rear surface of a reflection plate.
2. Description of the Related Art
A liquid crystal display is a device to display a desired image by controlling light transmissivity of liquid crystal cells arranged in a matrix according to image signal information. A back light unit illuminates light to form an image on a liquid crystal panel.
The liquid crystal display includes a liquid crystal panel with liquid crystal cells to form unit pixels, and a driving unit to drive the liquid crystal cells, and a back light unit to uniformly supply light to the liquid crystal panel.
The back light unit includes a light source to emit light to be illuminated to the liquid crystal panel, a reflection portion to reflect light emitted from the light source to the liquid crystal panel, and an optical sheet to diffuse light emitted from the light source and the reflection portion to be uniformly illuminated on the liquid crystal panel.
In addition to commonly-used cold cathode fluorescence lamps (CCFL), light emission diodes (LED) are recently used as the light source. In a case of using the light emission diodes (LED), forming a light source corresponding to a large-sized liquid crystal panel is beneficial and, particularly, providing a back light unit having a thin thickness is possible. Accordingly, the use of the light emission diodes is on an increasing trend.
In the liquid crystal display using the light emission diodes (LED) as the light source, a number of light emission diodes are arranged on a printed circuit board (PCB) having a power supply circuit at specific intervals. A reflective sheet is attached to a front surface of the printed circuit board to efficiently reflect light.
The printed circuit board is fixed on an inner surface of a lower chassis to support between the liquid crystal panel and the back light unit. However, finishing opposite sides of the lower chassis with additional reflective members to prevent light of the back light unit from leaking out through opposite sides of the lower chassis is necessary. Further, a reflective sheet is additionally attached to the surface of the printed circuit board with the light emission diodes to increase reflectivity.
Further, in the conventional liquid crystal display, a thermally conductive part is additionally disposed between the printed circuit board and the lower chassis to emit heat generated from the light emission diodes disposed on an inside of the lower chassis. Accordingly, as a number of parts increases, a cost of the product increases.